This project will examine the biological basis of age-related changes in human sexuality, with a particular emphasis on hormonal factors. Attempts will be made to correlate hormonal changes during menopause and after in women, and during aging in men, with specific aspects of change in sexual function. Double blind placebo crossover experiments will be performed in postmenopausal women to examine the roles of estrogen, progesterone and testosterone in the causation and correction of post-menopausal sexual dysfunction. Earlier findings that testosterone contributed to a small but significant extent in the sexual decline of aging men will be followed up in two main directions of research: In replacement therapy experiments attempts will be made to determine if the sensitivity of men to the sexual effects of androgen changes with age. Second, the goal of understanding the behavioral mechanism of action of androgen will be pursued. Psychophysiological tests will be utilized to measure responses during sexual arousal of men and women, produced by erotic film and fantasy. Specific examination of possible changes in systems will include assessment of tactile sensitivity thresholds and somatosensory evoked potentials with varying hormone levels and age.